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Reviewer: Srajan Ebaen
Financial Interests: click here
Source: APL HiFi NWO 3.0-GO; Ancient Audio Lektor Prime; Raysonic Audio CD-168
Preamp/Integrated: Supratek Cabernet Dual; ModWright LS-36.5 with PS 36.5; Wyetech Labs Jade; Almarro A318B; Melody I2A3; APL Hifi UA-S1; Woo Audio Model 5; Yamamoto HA-02
Amp: 2 x Audiosector Patek SE; 2 x First Watt F4, 1 x F5; Yamamoto A-08s; Fi 2A3 monos; Yamamoto A-09S
Speakers: DeVore Fidelity Nines; WLM Grand Viola Monitor with Duo 12; Rethm Saadhana; Mark & Daniel Ruby and Maximus Monitor with optional OmniHarmonizer; Haigner Rho [on review]; JohnBlue Audio Art JB8 [on review]; Acoustic System International Tango [this review]
Cables: Ocellia Silver Signature loom; Crystal Cable Ultra loom; Crystal Cable Reference power cords; Stealth Audio Indra and Meta Carbon; Acoustic System International Liveline [on review]
Stands: Ikea, with re-purposed Ikea butcher block platforms
Powerline conditioning: 2 x Walker Audio Velocitor S fed (from custom AudioSector 1.5KV Plitron step-down transformer with balanced power output option for 120V gear)
Sundry accessories: Walker Audio Vivid CD cleaner; Walker Audio Reference HDLs; Furutech RD-2 CD demagnetizer; Nanotech Nespa Pro; extensive Acoustic System resonator tuning throughout the house
Room size: 'Elephant Cave' sound platform 3 x 4.5m with 2-story slanted ceiling; four steps below continues into 8m long open kitchen, dining room and office which widen to 5.2m with 2.8m ceiling; sound platform space is open to 2nd story landing and 3rd-floor studio; concrete floor, concrete and brick walls, converted barn with no parallel walls nor perfect right angles; short-wall setup with speaker backs facing the 8-meter expanse
Review Component Retail: €13.500/pr [Silver + Basic resonators inside]; €15.300/pr [Basic + Gold + Silver]; €18.500/pr as reviewed [Basic + Gold + Platinum]; €25.000/pr [Basic + Gold + Platinum + diamond tweeters]

At least in these pages, Franck Tchang of Acoustic System International needs no introduction. If you've still somehow skipped him, simply check the alphabetical archive under 'A'. You'll find prior reviews of his infamous acoustic resonators, noise filters and Liveline interconnects. As for the it-takes-two-to-Tango loudspeakers? Their genesis was not concerned with audiophiles but musicians. It was to allow graduate students of the Paris music conservatory to study great recorded performances of the last century. "Professors there complained that modern speakers made no music but only compressed sounds." To rectify the situation, the conservatory commissioned Mr. Tchang who, franckly, was also inspired to build a speaker for his own personal use. This simply became the impetus and thus the Tango was born.

For this project, Franck had a few goals: Widest possible bandwidth; no electronic frequency-domain corrections; 6dB/octave filters; fewer parts to preserve energy; an acoustically optimized enclosure with high living-room appeal. The transducers in this 5-driver design are custom-made to his specifications in the Far East. There are three paralleled 8" carbon-fiber woofers; a composite 5" carbon/paper midrange; and a 1" silk dome. (A true diamond -- not white sapphire -- tweeter is optional). The three-way crossover points are 280 and 2800Hz. This minimum-phase filter network is assembled by Jensen in Brøndby Denmark. They populate it with premium Jensen components; ASI mounts it in a separate sealed chamber below their lowest woofer.

The nominal impedance rating is 5.6 ohms. That figure alone completely misses the picture. As the graph shows, everything just below 1kHz is 6 ohms ruler flat. This fact isn't at all lost on low-power tube amps. They take to the Tango in a big way and are quite oblivious to its 89dB voltage sensitivity as long as there's sufficient gain in the chain. Minimum impedance sits at 2.83 ohm and 5.3kHz, max impedance at 11.6 ohm and 1.8kHz. The power-critical range below 300Hz thus is completely non-critical when it comes to reactivity. That makes the Tango into a dream dance partner.


Published bandwidth is 18Hz to 25kHz +/-3dB. The 65kg, 121 x 65 x 38cm HxDxW boat-hull enclosure is steeply curved to be significantly narrower in the back than front. It uses no absorptive filler whatever. Like the integral high-gloss black plinth, it runs thick Walnut for divider braces. Those form the individual inner compartments. The two between the three woofers are of the window-pane sort. They sport four big holes. The upper two dividers for the tweeter and midrange chambers are solid. Franck disdains damping materials. "They kill off fine harmonics and transparency. No instrument needs internal absorbers to sound right." Our Vietnamese auteur revolutionized the French diamond trade by selling diamond jewelry to the Carrefour Group; built his own guitar from scratch; and invented the acoustic resonators which appear not to be based on any recognizable acoustic sciences text books. Yet they are devilishly effective. Predictably then, copy-cat and 'inspired by' variants have already appeared - and disappeared in some cases as Franck Tchang is a patent holder for this specific technology.


Back to the Tango. As the absence of the usual port saddle proves conclusively, this is far from your typical vented alignment. The elongated oval opening above the single-wire terminals is not a conventional port nor does it employ an inner tube of even minimal length. Sitting directly in its path, this small slot has three acoustic resonators which are sized specifically for the Tango. Those resonators "clean up unwanted low-frequency resonance produced by the internal back pressure as well as enhance overtones". The resonators of the reviewed top 'R' version are the Basic, Gold and Platinum. Two lower-priced versions simplify the resonator array but can be upgraded to reference status at any time. Simply swap/add the costlier resonators. With 650 watts of continuous power handling, the Tangos should be conditioned "very loud if possible" to smooth the overall sound and extend the bass with fully developed harmonics. After break-in, all mounting screws should be checked and retightened without being ham-fisted. More on that very critical bit on the next page.

The discrete tweeter and midrange compartments communicate with the tri-partitioned woofer enclosure via very small strategic holes inside their solid Walnut dividers to equalize internal pressure conditions. They additionally communicate with the room air through a hole each in the cabinet's black-lacquered spine. Like all other Tchang inventions, this air tuning system is empirical. It's a far cry from any Loudspeaker Cookbook conventions. In previous reports on Tchang products, I've coined the term Franckenese. It means to indicate that Tchang explanations arise from a very personal perspective of inquiry and even 'extra-aural' perceptions that go beyond sound. Hard-core engineering types won't have ready equivalents for how he uses certain terms. Nobody can gracefully translate them into recognizable Physics. But Franck Tchang's entire acoustics approach revolves around a pressure-to-tension conversion process. Here's a bit of Cyprus lore whose veracity I cannot confirm except that the people who told me are mature trustworthy friends.


Apparently, Limassol harbor in Cyprus is routinely bedeviled by small twisters, i.e. very focused spiraling gusts which eventually rush through the streets to overturn Vespas and blow out store windows. Unlike full-blown tornadoes, the path of these twisters is usually narrow - some 20 feet wide as I was told. With the UK army maintaining a presence on this former British colony, they've purportedly been quite successful at neutralizing many developing twisters. They lobby grenades at them so that one violent air disturbance (the twister) is cancelled by another (the exploding grenade).

Whether true or urban myth, it certainly ties into Franck's world view. His resonator technology neutralizes zones of air compression and unequal pressure build-up. Think corners for example where bass energy compounds. Or negative spaces like stair cases. After all, sounds transmit through air. Acoustic disturbances are various phenomena which occur in the air. Unless hermetically sealed, the air inside a dwelling communicates from room to room and closet to closet and even with the outside. By equalizing air pressure differentials that are created by the geometry of a dwelling or room when disturbance generators activate it (loudspeakers from the inside, wind from the outside for example), acoustic resonators and related Tchang tuning devices can powerfully relieve living and work environments of 'negative' acoustic phenomena (compression zones). This goes well beyond sonics.


"Sound is just a feedback mechanism for those not sensitive enough to feel the effects of my pressure-to-tension conversion work in the air with their bodies and brains. I can set up my resonators and noise filters just by observing how my body responds. From experience, I can also see or intuit obvious problem areas. Then I observe how my voice or foot fall changes in timbre or resonance as I walk through a place. In certain areas, the breathing becomes shallow or labored. Other areas might feel cold as though there was an energetic inversion or vacuum. When a room feels open and even, it will sound good. When it sounds good, it is properly tuned and feels good. Regardless of which direction you approach it from, the outcome is the same - an acoustically benign, psychosomatically healthy space." Besides concert halls, Franck Tchang has treated yoga centers, massage and meditation studios. Their focus was plainly on Feng Shui energetics, not sonics. In some of these spaces in fact, they don't play back any music at all.

While appearing to be yet another vertically baffled loudspeaker of convention, the Tango is fully informed by the Acoustic System approach. It exploits the same thinking. For example, each of the three bass chambers includes a small Indian rosewood disc. As delivered, the grain of this disc as also marked with an arrow is oriented in a 90° angle to the woofer cone. By rotating this disc (after temporarily removing the corresponding woofer), bass damping can be adjusted. Removing one disc altogether to demonstrate its necessity, Franck showed how the tonality of the carbon cone changes by tapping it with his finger. With the rosewood disc behind it, it sounds like paper; without it, like cardboard. He wanted a paper sound with greater mechanical stiffness. Enter the Carbon fiber construction. His know-how of material sciences simply converts the Carbon fiber sound to paper with the wooden disc. It reads far more mystifying than Franck's hands-on demonstrations. That made the point in a readily audible, very practical manner.

Even the footers are unusual, being bonded stacks of different wooden discs which hide three internal air cavities and sport very small escape holes. Far from haphazard, the designer spent a long time experimenting with various woods to optimize the important interface between speaker and floor. The internal wiring is sourced from a German medical supplier, the single pair of binding posts is by Furutech. The very thick and deep lacquer is flawlessly applied. In conjunction with the narrowing profile and two-tone color scheme, it makes for an exceedingly elegant, fine piece of audio furniture that you'll be proud to display upstairs rather than hide away in the usual audiophile basement dungeon.